This interactive spectrogram visualizes audio frequencies in real time, displaying a scrolling heatmap of sound data across time. The project uses the Web Audio API to analyze audio buffers and D3.js (v5) for rendering the SVG axes and canvas-based spectrogram. Playback controls allow users to load and analyze sound files, with the frequency analysis performed via `AnalyserNode.getByteFrequencyData`. The visualization animates as audio plays, building up the spectrogram view.